A technique for cutting metal which has been used for some time is that of imposing a low voltage high current source between the work to be cut and a carbon electrode. The electric arc formed between the electrode and the work piece creates an area of high heat intensity which melts a localized area of the work piece. To remove the molten metal formed in the localized area an air stream is directed to blow it away.
In order to effectively accomplish cutting of metal using this technique a holder is required to perform the plural function of holding the carbon arc electrode in a way so that the extension of the electrode from the holder can be easily adjusted, plus providing a means of maintaining low resistance electrical connection with the electrode, and at the same time providing a means of directing air along the electrode to blow away molten metal formed in the cutting process.
Towards this goal others have devised electrode holders, an example is that of U.S. Pat. No. 2,935,597. One problem with the known type of holders, including that taught in this previously issued patent, is that it is necessary to make good electrical contact between the holder and the electrode while at the same time providing an easy means of adjusting the length of the electrode relative to the holder. The arc formed by the electrode with the molten metal gradually eats away the carbon electrode so that it must be periodically extended relative to the holder. For these reasons, the common means of using carbon arc electrodes is to utilize a holder which provides for adjusting the length of the electrode extension from the holder. Because of the high currents involved in the apparatus, any resistance caused by the contact causes high temperatures to develop and any imperfection in the contact between the holder and the electrode results in arcing. The arcing not only reduces the life of the electrode but generates substantial amount of additional heat. For this reason, it is highly important that a minimum of electrical resistance exists between the holder and the electrode, while at the same time providing means of easily moving the electrode relative to the holder.
It is therefore an object of this invention to provide an improved holder for carbon arc electrodes. More particularly, an object of this invention is to provide an improved holder for carbon arc electrodes including improved means of achieving and maintaining effective electrical connections between the holder and the electrode.
Still more particularly, an object of this invention is to provide a holder for carbon arc electrodes including means of providing improved electrical contact between the holder and the electrode and in addition, providing means whereby the adjustment of the electrode relative to the holder is easily and expeditiously accomplished by the user.
Another object of the invention is to provide a holder for carbon arc electrode utilizing a flow of air to blow the molten metal away from the area being cut, including improved means of directing the flow of air along the electrode.
These general objects, as well as other and more specific objects of the invention, will be fulfilled in the following description and claims, taken in conjunction with the attached drawing.